I am looking at building a new PC to meet today's standards in media and CAD computing. I Don't want to shell out hundreds of dollars to MS and buy a new OS when my old IDE drive is in excellent shape and contains Win Vista Home Premium 32bit. Would I be able to plug this hard drive into the mobo and, with a few BIOS edits, boot my 32bit OS on a 64bit AMD tri-core processor? The board I am using is a BIOSTAR AM3. I am also going to attempt to unlock the 4th core.
Depends -- Do you have the install CD ?? -- once you place the old drive in the new system it will need to reexamine the system and replace the various drivers etc. for the new components and delete the old ones -- and in order to do this you will need to boot from the install CD and run a Repair installation (you'll need the install cd because the files needed are not copied to your old hdd during the old install - only the ones needed for that system are copied so you will need the correct files for the new system from the install disk in order to complete the process --- Also after running the Repair installation you will most likely need to reauthenticate the install by reentering the key code from the sticker on the case to validate the installation or it will stop working in IIRC 60 days -- because changing the MOBO is considered a major modification and requires revalidation in most cases.
So - Yes it can be done but you still need the key code and install CD to accomplish it. (and if you have both of those in most cases you are better off just doing a new installation and reinstalling your programs fresh so that old problems are not brought to the new system !!)